Partial discrete fourier transform-spread in an orthogonal frequency division multiplexing system

A system comprising:

• a serial-to-parallel quadrature amplitude modulation (QAM) module configured to receive a first stream of serial data bits and to convert the first stream of serial data bits into a set of parallel QAM symbols;
• and
• a partial discrete Fourier transform-spread (DFT-S) module communicatively coupled to the serial-to-parallel QAM module, the partial DFT-S module configured to apply a partial DFT-S technique to transform a block of low-frequency subcarriers into a single-carrier QAM signal, wherein:
• the single-carrier QAM signal bears information of a first subset of QAM symbols from the set of parallel QAM symbols;
• the partial DFT-S module includes a discrete Fourier transform (DFT) module and an inverse discrete Fourier transform (IDFT) module;
• the IDFT module is configured to transform one or more remaining QAM symbols from the set of parallel QAM symbols to form one or more subcarriers, wherein each of the one or more subcarriers bears information of a corresponding QAM symbol from the one or more remaining QAM symbols;
• and
• the IDFT module is configured to generate a hybrid signal that includes the single-carrier QAM signal and the one or more subcarriers, wherein the hybrid signal is configured to transmit to a receiver.

A method comprising:

• receiving a first set of parallel pulse amplitude modulation (PAM) symbols or quadrature amplitude modulation (QAM) symbols to be transmitted in a low frequency band of a composite channel that includes a digital-to-analog converter (DAC), a driver amplifier, an electro-optical converter, an opto-electrical converter, and an analog-to-digital converter (ADC);
• receiving a second set of parallel QAM symbols to be transmitted in a high frequency band of the composite channel;
• transforming the first set of parallel PAM or QAM symbols into a single-carrier PAM or QAM signal that occupies the low frequency band, wherein the single-carrier PAM or QAM signal bears information of the first set of parallel PAM or QAM symbols;
• transforming the second set of parallel QAM symbols into a discrete multitone (DMT) signal that occupies the high frequency band, wherein the DMT signal bears information of the second set of parallel QAM symbols;
• generating a hybrid signal that includes the single-carrier PAM or QAM signal and the DMT signal;
• and
• transmitting the hybrid signal.